The present application relates to an electrode that includes an active material layer, to a secondary battery that uses the electrode, and to a battery pack, an electric vehicle, an electric power storage system, an electric power tool, and an electronic apparatus that use the secondary battery.
In recent years, various electronic apparatuses such as a mobile phone and a mobile information terminal device (a PDA) have been widely used, and it has been demanded to further reduce the size and the weight of the electronic apparatuses and to achieve their longer lives. Accordingly, as an electric power source, a battery, in particular, a small and light-weight secondary battery capable of providing high energy density has been developed.
In these days, it has been considered to apply a secondary battery to various other applications in addition to the electronic apparatuses. Examples of such other applications may include a battery pack attachably and detachably mounted on the electronic apparatuses or the like, an electric vehicle such as an electric automobile, an electric power storage system such as a home electric power server, and an electric power tool such as an electric drill.
There have been proposed secondary batteries that utilize various charge and discharge principles in order to obtain battery capacity. In particular, attention has been paid to a secondary battery that utilizes insertion and extraction of an electrode reactant, because higher energy density is achieved thereby.
A secondary battery includes a cathode, an anode, and electrolytic solution. The cathode includes a cathode active material layer, and the cathode active material layer includes a cathode active material that inserts and extracts the electrode reactant. The anode includes an anode active material layer, and the anode active material layer includes an anode active material that inserts and extracts the electrode reactant.
In such a secondary battery, it is important to improve battery characteristics such as battery capacity; however, it is also important to secure safety. Accordingly, various considerations have been given on the configuration of the secondary battery.
Specifically, in order to improve high-temperature conservation characteristics, etc. after charge operation, ammonium polyphosphate, etc. are contained in a cathode mixture or in an anode mixture (for example, see Japanese Unexamined Patent Application Publication Nos. H10-255389, 2010-251217, and 2001-015166). In order to improve low-temperature characteristics, etc., ammonium polyphosphate, etc. are contained in the electrolytic solution (for example, see Japanese Unexamined Patent Application Publication No. 2005-353579). In order to enhance ignition tolerance, ester phosphate, etc. are provided in part of a separator (for example, see Japanese Unexamined Patent Application Publication No. 2009-301746). In order to cause the secondary battery to be in a safe state when an abnormal incident occurs, ammonium polyphosphate, etc. are contained inside a housing of the battery (for example, see Japanese Unexamined Patent Application Publication No. 2009-301798). In order to secure heat tolerance, etc., melamine cyanurate, etc. are contained in a resin composition of a battery container for the secondary battery (for example, see Japanese Unexamined Patent Application Publication No. H10-214603).